OVERALL DESCRIPTION: (Applicant's Description) The proposed Cancer Research Network (CRN) consists of research programs, enrollee populations and databases of 10 HMO Research Network members - Group Health Cooperative of Puget Sound, Harvard- Pilgrim Health Care, Henry Ford Health System, Health Partners Research Foundation, Fallon Health Care System represented by the Meyers Primary Care Institute, and Kaiser Permanente divisions in Hawaii, Oregon, Washington, Northern and Southern California, and the Rocky Mountain area. The goal of the CRN is to determine and improve the effectiveness of cancer control interventions that span the natural history of major cancers among diverse populations and health systems. The 10 HMOs, with approximately nine million enrollees, are distinguished by their longstanding commitment to prevention and research, and collaboration among themselves and affiliated academic institutions.